The present invention relates to a polishing machine. More precisely, the present invention relates to a polishing machine comprising a polishing plate, whose upper face is formed as a polishing face, for polishing a wafer, whose bottom face is pressed onto the polishing face; a holding section having a concave section, whose bottom face is opened, the holding section being capable of horizontally moving toward a position above the polishing plate, vertically moving with respect thereto, and rotating in a plane parallel thereto; a carrying plate, which is provided in the concave section of the holding section, for holding the wafer on a bottom face, the carrying plate being capable of vertically moving in the concave section; and a press mechanism for pressing the carrying plate toward the polishing plate by fluid pressure.
Recently, silicon wafers on which integrated circuits are formed, have been required to have highly uniform thickness and highly plane surfaces. To satisfy these requirements, a polishing machine having a press mechanism for pressing carrying plates toward polishing plates by fluid pressure was invented. This polishing machine was disclosed in the Japanese Patent Kokai Gazette No. 4-13567. In the polishing machine disclosed in the gazette, a cylindrical metal bellows, which is capable of extending and shrinking upward and downward, is provided on an upper face of a carrying plate. Compressed air, which is one example of fluid, is supplied into the metal bellows so as to uniformly press the upper face of the carrying plate. Since air pressure is uniformly applied to the upper face thereof, a silicon wafer, which is held on a bottom face of the carrying plate, is uniformly pressed onto a polishing face (an upper face) of a polishing plate. Therefore, the silicon wafer can be polished to have highly uniform thickness and highly plane surfaces.
However, the conventional polishing machine has the following disadvantages.
The metal bellows extends downward when compressed air is supplied. Thus a holding section, which accommodates the carrying plate and the metal bellows, must be large in the vertical direction, so that the polishing machine must be larger and heavier.
Furthermore, friction between the silicon wafer and the polishing plate makes the carrying plate rotate with respect to the holding section while the silicon wafer is polished. The metal bellows is twisted by the rotation, so that stress continuously acts on the metal bellows. As a result of the stress, the bellows is likely to be severely damaged.